Deaerating heater



Dec. 6, 1949 c. H. BERGQUIST 2,490,294

DEAERATING HEATER Filed Oct. 27, 1945 INVENTOR WITNESSES:

ATTORNEYS.

Patented Dec. 6, 1949 DEAERATING HEATER,

Carl Hugo Bergquist, Forest Hills, Pa., assignor to Elliott Company,Jeannette, Pa., a corporation of Pennsylvania Application October 27,1945, Serial No. 625,006

3 Claims. 1

This invention relates to apparatus for heating and deaerating boilerfeedwater by means of steam, and more particularly to such apparatus inwhich the steam enters the deaerating tank through a nozzle at highvelocity.

In order to deaerate boiler feedwater it may be heated by steam in adeaerating tank, and, as the temperature of the water approaches thesaturation temperature, the solubility in the water of such gases asoxygen and carbon dioxide approaches zero. These non-condensible gasestherefore are liberated from the water and are swept to the vent of thedeaerating tank by the flow of steam.

In some deaerators the incoming steam is sprayed from nozzles into thewater to atomize the water in order to promote heating and deaeration.When such deaerators are operated at light loads the water is allowed toenter the outlet of the steam nozzle and flow backwardly into the nozzlewhere it forms an obstruction that holds back the steam until sufiicientsteam pressure is built up to blow this body of water out of the nozzle.The steam and water therefore leave the nozzle in intermittent bursts.It is obvious that good atomization and deaeration can not be obtainedin this way.

There are other deaerators in which the feedwater enters the steamnozzle some distance behind its outlet, and the water and steam aremixed together in the nozzle. To produce good mixing at high as well aslow loads, it has been proposed to automatically vary the size of thenozzle in accordance with the load, but this involves the use of movingparts inside the tank where they are diflicult to service in case theyget out of order. It also increases the cost of the deaerating apparatusconsiderably.

It is among the objects of this invention to provide an inexpensivedeaerating heater in which a spray of steam thoroughly and continuouslymixes with the water being heated by it, in which the water can not runback into the steam nozzle from its outlet, and in which thorough mixingof steam and water occurs at all loads without the use of moving parts.

In accordance with this invention water to be heated and deaerated isintroduced into a deaerating tank having a vent through which escape thenon-condensible gases liberated from the water. The tank is alsoprovided with a steam inlet to which is connected a combined mixing andatomizing nozzle that has an outlet preferably located near the centerof the tank. One wall of the nozzle is provided with an inlet openingfor water which is conducted to it from the area where it enters thetank. Inside the nozzle, between its outlet and the water inlet, thereis a transverse scrubber plate against which steam projects water thatenters the nozzle through the water opening, thereby producingturbulence and thorough mixing of the steam and water before it leavesthe nozzle. The nozzle has an elevated portion between its outlet andthe water inlet to keep water outside the nozzle from flowing over theupper edge of the outlet unless the water rises above the elevatedportion. In such a case any water flowing over the upper edge of theoutlet is atomized by the steam and water mixture discharged from thenozzle outlet, so that the water can not flow back into the nozzle fromits outer end. This nozzle therefore produces continuous, thoroughmixing of steam and water at any load.

The preferred embodiment of the invention is illustrated in theaccompanying drawings in which Fig. 1 is a vertical section through mydeaerating heater; Fig. 2 is a similar section of the heater, partly inelevation, taken on the line IIII of Fig. 1; and Fig. 3 is a horizontalsection taken on the line III- II of Fig. 1.

Referring to the drawings, relatively cold boiler feedwater enters oneside of the upper end of a deaerating tank I and is conducteddiametrically across it through a horizontal spray pipe 2. This pipe maybe provided with two parallel rows of closely spaced jets 3 extendingalong it for supplying the water in two sheets upwardly and outwardly inopposite directions against straight and cylindrical baiiles. Thecylindrical baflle 4 extends downwardly a short distance from the top ofthe tank aroundthe two spaced pairs of parallel straight baflles 6 and Ithat likewise are secured to the top of the tank. The upper wall of thespray pipe between the two rows of jets may be made flat to avoid waterhammer and may be covered by a fiat plate 8 that projects a shortdistance laterally from the pipe to control the upper sides of the twosheets of water so that they will not spray up into the vent that willbe described later. The sprayed water flows from the baffles down into avertical cylinder 9 which encircles the lower end of the cylindricalbafl'le and is spaced from it and the side of the tank. The cylinder maybe supported from the side of the tank by circumferentially spacedmembers ll. This cylinder forms the side wall of a pan the bottom walll2 of which is inclined in order to form a drain member.

The center of the top of the tank is provided with an opening in which ashort vertical vent pipe I3 is mounted. The lower end of this pipecommunicates with the top of a narrow gas-receiving hood 14 extendinghorizontally across the tank directly above the spray pipe to which itis parallel. The bottom of this receiver or hood is provided with a longrectangular opening which forms the entrance to the vent. The lower sideedges of the hood, which form opposite sides of the vent entrance, areso positioned relative to the spray jets in the pipe that the sheets ofwater issuing therefrom flow outwardly across those edges and therebyform a water curtain that closes the entrance to the vent. To equalizethe pressure drop along the length of the hood a horizontal baiile platei6 is mounted inside the hood with its sides spaced therefrom. This ventconstruction is part of the subject matter of my copending applicationSerial No. 608,999, filed August 4, 1945, now Patent No. 2,452,716 inwhich its construction and operation are described. It is unnecessary inthis specification to go into a description of the vent any further thanto point out that the non-condensible gases liberated from the heatedwater escape through the vent without the loss of an appreciable amountof steam. A cont-.ibuting factor to this highly desirable result is apressure control valve I! that is mounted on top of the vent pipe. Asthe construction and operation of this valve form no part of the presentinvention, further description of it will not be given herein. It isfully described in my copending application. The side of the tank may beprovided with a normally closed access opening l8.

In order to heat the water in the tank, steam is sprayed into the water.This is done by providing the upper portion of the side wall of the tankwith a steam inlet 20 to which a nozzle is connected inside the tank.The nozzle preferably has a vertical section 2| extending downwardlyfrom the steam inlet with the side wall of the tank forming one side ofthe nozzle. The upper portion of the nozzle'projects into the adjoiningdeep side of the pan formed by cylinder 9 and drain member l2. At thelower end of vertical section 2| the nozzle turns and extends inwardlyand upwardly to approximately the center of the tank, thereby forming aninclined nozzle section 22. The upper end of this inclined section isspaced below the pan and is provided with an outlet 23 that openslaterally; that is, the upper wall of the outlet is substantiallyhorizontal so that vapor issuing from the nozzle is directed more orless horizontally across the tank to prevent it from being blowndirectly up into the space between the pan and the tank. The oppositesides of the nozzle are formed from vertical plates 24 that also extendupwardly from the inclined section to the bottom of inclined drainmember I! to which they are welded. Thus, a chamber is formed directlyabove the inclined section of the nozzle. Water issuing from spray pipe2 collects in the pan from which it is discharged into this chamberthrough a rectangular opening 26 in the lower end of drain member l2.This member also may be provided with an access opening 21 that isclosed by a door plate 28 bolted in place.

Feedwater sprayed from pipe 2 against the baflles attached to the top ofthe tank is heated preliminarily by uncondensed steam that has riseninto the top of the tank. This water falls into the pan below thebailles and is discharged through opening 26 into the water-collectingchamber formed on top of inclined section 22 of the steam nozzle. Thelower wall of this chamber, which is the upper wall of the inclinedsection of the nozzle, is provided near its lower end with atransversely extending slot 30 that forms an inlet passage for waterinto the nozzle from the chamber above. The shape of the inclinedsection of the nozzle in vertical section preferably is somewhat like aventuri so that steam passing upwardly through it past the slot at highvelocity will have an iniector effect that will draw the water throughthe slot into the nozzle. A large head of water to force the waterthrough the slot is unnecessary.

Inside the nozzle between this water inlet Ill and the outlet of thenozzle there is a baifle plate 3| extending across the nozzle to thelower wall of which it is secured. The top of this plate is only a shortdistance below the upper wall of the nozzle, so that a restricted port32 is formed between them. This plate forms a scrubber against which thesteam projects water that has entered through slot 30. By the time thewater has splashed against the plate and then been forced by the steamthrough narrow port 32, the water is thoroughly broken up and mixed withthe steam. This occurs even at very light loads when, in the absence ofthe scrubber plate, water might periodically collect in the lower end ofthe nozzle and then be blown out as a slug. The entrained water in mydeaerator is heated efliciently by the steam, and non-condensible gasesare liberated from the water as it enters the lower pressure area belowthe pan. The hot water falls into the bottom of the tank which serves asa reservoir from which feedwater is pumped out through outlet 33.

Under light loads all of the water discharged from the pan will enterthe nozzle through the water inlet slot 30. However, under heavy loadsthere may be so much water pouring from the pan into the collectingchamber below it that the steam will not be able to draw it throughinlet 30 fast enough to prevent the water from rising in the chamberhigh enough to escape from it by overflowing the outlet end of thenozzle. In such a case, water that flows over the upper edge of thenozzle will be caught by the high velocity stream of mixed steam andwater issuing from the nozzle and will be atomized by it. The atomizedwater is quickly heated by the steam.

The overflow from the water-collecting chamber is at a level slightlybelow the bottom of steam inlet 20 so that if the steam is shut oil!water can not rise high enough in the vertical section of the nozzle torun back into the steam conduit.

In a deaerating heater constructed in accordance with this inventionthere is continuous and thorough mixing of steam and water at all loadswithout the use of moving parts to compensate for changes in load, andwithout a large head of water inside the tank which wouldtake up spaceneeded for the storage of the heated and deacrated water. At some loadsthe nozzle will serve only as a scrubber nozzle because no water willflow over the upper edge of its outlet. At higher loads, the only timewhen water overflows the water-collecting chamber and falls into thespray issuing from the nozzle, the nozzle will function also as anatomizing nozzle. Therefore, regardless of load, all of the water willbe broken up into a finely divided state and thoroughly mixed with thesteam. At no time can water be blown out of the nozzle by the steamwithout satisiactorily mixing with it.

According to the provisions of the patent statutes, I have explained theprinciple and construction of my invention and have illustrated anddescribed what I now consider to represent its bestembodiment. However,I desire to have it understood that, within the scope of the appendedclaims, the invention may be practiced otherwise than as specificallyillustrated and described.

I claim:

' 1. A deaerating heater comprising a deaerating tank having a vent forescape of non-condensible gases, means for spraying water inside thetank, the tank also being provided at one side with an inlet tor steam,a combined mixing and atomizing nozzle in the tank connected to saidsteam inlet and having a portion extending downwardly from the inlet andanother portion inclined upwardly from said first portion andterminating in an outlet near the center of the tank, the upper wall ofsaid inclined portion being provided near its lower end with an inletopening for water, substantially parallel side wall members closing thespace between said upper wall and said downwardly extending portion ofthe nozzle and rising above said outlet, and a pan mounted in the tankfor collecting water sprayed from said means, the bottom of the panbeing spaced above the nozzle outlet and being inclined downwardlytoward said downwardly extending portion of the nozzle, said pan bottomengaging the tops of said side wall members and being provided with anopening between said members for emptying said water into the spacebetween them, any water rising high enough between said side wallmembers to flow over the upper edge oi. said outlet being atomized bythe steam and water mixture discharged from the nozzle outlet.

2. A deaerating heater comprising a deaerating tank having a vent forescape of non-condensible gases, means for delivering water to the tank,the tankalso being provided with an inlet for steam, a combined mixingand atomizing nozing to produce thorough mixing, said plate forming inthe nozzle a restricted port through which the steam will carry thewater at high velocity.

3. A deaerating heater comprising a deaerating tank having a ventfor-escape of non-condensible gases, means for spraying water inside thetank, the tank also being provided at one side with an inlet for steam,a combined mixing and atomizing nozzle in the tank connected to saidsteam inlet and having a portion extending downwardly from the inlet andanother portion "ining substantially Venturi-shape to form a threat atsaid inlet opening for reducing the steam pressure at that point so thatwater can enter the nozzle through said opening, and a transversescrubber plate in the nozzle between its outlet and said opening andagainst which said steam projects water -fromsaid opening to producethorough mixing, said plate forming in the nozzle a restricted portthrough which the steam will carry the water at high velocity, any waterrising high enough in said chamber to escape through said overflow flowsover the upper edge of the nozzle outlet and is atomized by the'steamand water mixture discharged therefrom at high velocity.

CARL HUGO BERGQUIBT.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

